Well, since there still is some curiosity as to the heating of milk and
the cheese making process, let me do a quick overview of the process for
you.

Note:  it cannot be heated up on the stove directly, not only because the
hot spots can affect the taste but those also introduce other
inconsistencies such as color, smell, hardness/softness, etc.

1. pour milk into a pan
2. bring temperature to 90F
3. add [bacteria] culture starter, and keep it at 90F for 45 to 60 minutes
- this will "rippen" the milk by increasing it's ph and acidity, also
different bacteria is used for different type of cheeses
4. add diluted rennet and let it sit for 45 to 60 minutes, this will
curdle the milk and at the end you'll end up with a mass that resembles
tofu that has been heated in soup.
5. dice the curdle (cut into small pieces)
6. over the period of 30 minutes raise the temperature of the milk to
100F, and never raise more than 1F/minute.
7. It is cheese now, you can even eat it at this point. The remainder of
the instructions are different for every type of cheese that you make.

So, stiring the milk is ok in step 2, 3, but not after that.  The
temperature control is specially important in step 6 because movement will
cause the curdle to lose fat and protein which will affect the end result.
 Note that all times and temperatures (except for step 2 and 3) will
differ depending on the type of cheese you're making.

While it can take up to 4 hours to go from milk to cheese, the total
amount of time you spend actually doing anything is about 1/2 hour.  But
during those 4 hours you're required to stick around checking temperatures
and making adjustments to the stove.  The initial crockpot topic got
thinking about automating the process a bit, which would allow me to step
away for a while and do other things while milk became cheese all by
itself.

First I thought of using aquarium heaters directly in the milk, but that
proved to be a bad idea considering the temperatures involved, so I moved
on to aquarium heaters in the water container, which was better, but now
depending on the heat transfer between the masses, maybe many aquarium
heaters would be needed to be controlled because of the amount of heat
necessary.  That is when I started wondering how I could calculate the
heat and the transfer rates, etc.

Thanks.


-Mario
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